| Popis: |
A Loop Heat Pipe (LHP) is assembled and tested for removing up to 400 W from two vehicle CPUs, while keeping their temperature under 95°C and using a 2 m-distanced, 45°C-air cooled condenser, and working fluid R1233zd(E). The capillary evaporator wick uses a liquid artery wick supplying liquid to a sawtooth copper wall evaporator. This novel sawtooth structure extends the evaporation area, spreads the liquid, and allows for the vapor escape space, while minimizing the evaporator resistance. For the application flexibility, it is preferred to place the condenser away from the CPUs. The air-cooled condenser fan-power consumption is also important, influencing the condenser thermal resistance. The loop thermal-hydraulics are analyzed (including the wick effective thermal conductivity, permeability, and maximum capillary pressure) and modeled. These include the role of the liquid accumulation on the evaporator, and the partial, local wick dryout under statistical variation in the microlayer wick thickness. The condenser thermal resistance and pressure drop, the transfer lines pressure drops, and the accumulator volume, which can dominate and limit the overall performance, are addressed in the design selection. The model predictions are compared with the performance of the fabricated LHP under variable thermal load and CPU-condenser separation distance. Good agreements are found, under partial flooding at low thermal load, under partial dryout at high thermal load, as well as under thermal loads with peak evaporator performance. Further improvements realized in the second-generation evaporator wick is expected to raise the peak performance and the maximum thermal load significantly. |
